3D Printers

[Thalestris24]

1 hour ago, upahill said:

Ah, if it printed in that orientation then it shouldn't have failed at all. Your top layer infill looked like layer lines, and the cylindrical holes looked very neat so I assumed it was printed with the small rectangle overhanging. You mention that this part is a slider, if thats the case you may want to orient it so that the holes are printing vertically, you will have to tackle the overhang of that rectangle but wont get the stepped edges on the cylinders which could affect the motion of the finished product (Im not familiar with what you are printing but as a general rule I try to print cylinders and holes in vertical orientation)

Good luck with the reprint.

Yeah, something went wrong... There shouldn't have been any overhang. The holes look ok. The part affixes to a rod on which it slides in a relative horizontal motion. The rectangular bit at the top just allows it to mate with a hole in the case. A lens on a holder attaches to the top bit via its hole, and the mechanism is used to adjust the lens' focus. Although the assembly pic below shows a round hole, he must have changed it to a rectangular one. It does indeed mate correctly with a lens holder that I've already printed. The ball of wool may not affect its functionality but I won't know until I make the case and check .

 

Louise

 

[Stub Mandrel]

On 26/10/2019 at 14:12, Thalestris24 said:

Here's a pic of the break. I didn't 'whack' it, I just tapped it!

Could be slightly too cool print temperature or it might be udner-extrusion, try either or both off increasing the head temperature 5-10 degrees or raising the extrusion percentage by 5-10%

[Thalestris24]

Just now, Stub Mandrel said:

Could be slightly too cool print temperature or it might be udner-extrusion, try either or both off increasing the head temperature 5-10 degrees or raising the extrusion percentage by 5-10%

Thanks. I reprinted it (see below) with an infill of 60% and it seems good. I haven't actually tried whacking it but it doesn't have to be especially strong

Louise

[Thalestris24]

I spent hours printing this piece but something went wrong again. Again, where there's a overhang so I must be doing something wrong / have wrong settings. I had supports set - 'touching buildplate'. Thinking about it, I suspect I should have said 'everywhere'? Clearly, it didn't properly print supports for the overhang but was otherwise ok.

Any ideas/suggestions/advice?

Here is a pic of the piece showing the underside of the overhang (a bit of camera shake, but you can see it's a mess underneath). 

Here's roughly what it should look like:

Nice and flat underneath the overhang, obv  

Cheers

Louise

[Mognet]

That does look like a support issue. Try it with supports set to everywhere first. I'm sure that's what my slicers default to and I don't see problems like this

With that piece it looks like the supports should be generated between the top and bottom horizontal parts, mostly filling the area with an easily removable section. It's normally possible to check in advance where the slicer is putting supports by switching to the layer view

[Thalestris24]

7 minutes ago, Mognet said:

That does look like a support issue. Try it with supports set to everywhere first. I'm sure that's what my slicers default to and I don't see problems like this

With that piece it looks like the supports should be generated between the top and bottom horizontal parts, mostly filling the area with an easily removable section. It's normally possible to check in advance where the slicer is putting supports by switching to the layer view

Thankyou! Yes, that does sound like that will fix it Ah, I didn't twig I could see the supports beforehand! That's really useful to know - thanks!  

I'll try again tomorrow - fingers crossed!

Louise

 

[Chriske]

I'd split that part in two and bolt it together with to small bolts, nice and clean parts.
Did a quick drawing

[Thalestris24]

52 minutes ago, Chriske said:

I'd split that part in two and bolt it together with to small bolts, nice and clean parts.
Did a quick drawing

I reprinted it with supports 'everywhere' overnight and it's fine - the only trouble is I'm not sure how to remove the support which is a big lump between the top and bottom? Brute force?

Louise

[upahill]

2 minutes ago, Thalestris24 said:

I reprinted it with supports 'everywhere' overnight and it's fine - the only trouble is I'm not sure how to remove the support which is a big lump between the top and bottom? Brute force?

Louise

Should be reasonably brittle, I use a pair of sharp side cutters to clean up the edges once the bulk is removed.

[ejp1684]

Pliers to remove the supports (be quite firm with it!), sharp cutters and a file are how I get rid of supports.

Eric.

[Thalestris24]

34 minutes ago, upahill said:

Should be reasonably brittle, I use a pair of sharp side cutters to clean up the edges once the bulk is removed.

It's ok, I managed in the end - took some effort, lol. A combination of pliers and screwdrivers. I'm not strong enough for this - I'm gonna need some bigger muscles! I don't think it needs any cleaning up - should function ok. The only problem I have now is fitting the parts together:

The top is fine and mates with a top section (not shown in pic). There is a similar but shorter rod which is supposed to fit into a hole in the base but doesn't quite. It isn't a through hole (just a sort of depression) but I think I might have to convert it to a through hole in order to allow the bottom rod to fit into it. The reflection grating fits into the middle part (grey rectangle) and the whole should be able to rotate.

Louise 

Edited October 29, 2019 by Thalestris24

[tekkydave]

Holes always come out slightly smaller than expected due to the extra thickness of the filament. When designing its good to increase the size slightly to compensate. e.g. I always draw 5mm holes at 5.4mm and an M5 nut will just clear the sides when inserted. Obviously doesn't help you with this as someone else designed it. I find a round needle file is my friend in these cases. Might be worth buying a set for the future

Good to see you are getting on well with the new printer  - much faster than when I first started out in 2014.

 

 

[Thalestris24]

I managed it in the end - judicious application of emery paper It all fits together now and, hopefully, should function as intended:

Louise

[Gina]

Well done.  Coming on nicely

[Thalestris24]

2 hours ago, Gina said:

Well done.  Coming on nicely

Thanks! Am grateful for all the help and advice I've had from this forum I've printed nearly everything now - just the case and lid to do. The case is a big print job. I'd like to be able to do it without pausing but that might be difficult. It will probably have to wait until Friday.

Cheers!

Louise

[skybadger]

Have you got all the optics for this already Louise ? Very interested in the end result. 

[Thalestris24]

19 minutes ago, skybadger said:

Have you got all the optics for this already Louise ? Very interested in the end result. 

Not yet - I'll be looking at options for the optics soon. I also need to get the nuts, bolts and grub screws

Louise

[Thalestris24]

Am doing a 'draft' print of the Lowspec case - started it earlier at about 12:30. Should be done at about the same time tomorrow It's really so I can check out the layout and how things will (hopefully!) fit together. The placement of the two main lenses is very tight from a spacing point of view. Paul Gerlach changed the original camera lens size from 24.5mm to 30mm dia. He had to flatten one side of its otherwise circular lens holder. As it happens, I have two unused 6x30 finders. I was looking to use one or both objective lenses but... They are actually 31.2mm diameter so need to see whether slightly larger holders will still be able to fit together. They are nice, coated doublets. Just in case, I've also ordered some lenses from SurplusShed They are cheap (only $7.50 each) but there's no telling what condition they will actually be in until I get them. Have ordered a 600 line grating and the mirrors from Thorlabs. Should be coming on Wednesday from Germany and via UPS. Good service! However, they are out of stock of a 1" mirror so will have to look elsewhere for that by the looks of it. Ordered the reflective slit from Jeulin. So, I should have all the parts very soon! I've been making a start on learning the Fusion 360 software. Working my way through Lars Christensen's YouTube video tutorials for Absolute Beginners, so I hope to be able to make minor design adjustments to the Lowspec. Exciting, really, and all good fun!

Louise

 

[Merlin66]

Louise,

Sounds like things are progressing...if you consider the finder objectives, just check the focal length.....

Keep it going!

 

[Thalestris24]

4 minutes ago, Merlin66 said:

Louise,

Sounds like things are progressing...if you consider the finder objectives, just check the focal length.....

Keep it going!

 

Thanks and, yes I did. Fl of the finder objectives is about 100mm which will probably do. Paul's design was original 80mm for the camera lens, later changed to 100mm. And is 125mm for the collimation lens, but 100mm will still be ok. Both lenses can obviously be changed later, if necessary.

Louise

[Merlin66]

Louise,

The collimator lens focal length is designed to match the physical distance between the slit and the collimator lens. Not sure how much allowance Paul has designed into the arrangement.

 

[Thalestris24]

16 minutes ago, Merlin66 said:

Louise,

The collimator lens focal length is designed to match the physical distance between the slit and the collimator lens. Not sure how much allowance Paul has designed into the arrangement.

 

I don't have any drawings with measurements (unless I can somehow get them from the stl or gcode files?). I have a printout of the assembled case which seems to be close to actual. On the printout, the measured slit to collimator via the mirror is ~105mm which is short of the recommended 125mm fl. The collimator to grating distance is about 25mm. As I say, I can change the lenses if I need to but recycling unused, old finders if I can seems kind of nice.

Louise

ps the Simspec you gave me seems to allow some variation of lens focal lengths?

Edited November 4, 2019 by Thalestris24

[Merlin66]

Ok.

The distance from the collimator to the grating is non critical, has no impact on the collimator focal length.

[Thalestris24]

1 minute ago, Merlin66 said:

Ok.

The distance from the collimator to the grating is non critical, has no impact on the collimator focal length.

If I can manage to get my head around the details of the design theory, and also learn Fusion 360 well enough, I might try hacking an 'improved' version of the spectrometer some time in the future . Of course, one step at a time!  

Louise

[Merlin66]

A blatant plug....my book “Astronomical Spectroscopy for Amateurs” covers most of the design bases.

Some very helpful links also on the Webpage (see below).